Papers by Author: C.G. Oertel

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Authors: R. Hühne, B. Fels, R. Tamm, C.G. Oertel, Werner Skrotzki
Authors: R. Tamm, M. Lemke, C.G. Oertel, Werner Skrotzki
Authors: Burghardt Klöden, Werner Skrotzki, C.G. Oertel, E. Rybacki
Abstract: Polycrystalline samples of NiAl have been deformed in torsion in the temperature range 800K – 1300K. Deformation is accompanied by dynamic recrystallization, which with increasing temperature changes from continuous to discontinuous mode. Emphasis was put on the occurrence of continuous dynamic recrystallization, which will be discussed with respect to texture and microstructure.
Authors: Werner Skrotzki, R. Tamm, C.G. Oertel
Authors: Werner Skrotzki, R. Tamm, Burghardt Klöden, C.G. Oertel, L. Wcislak, E. Rybacki
Authors: P. Chekhonin, B. Beausir, J. Scharnweber, C.G. Oertel, J. Jaschinski, Tina Hausöl, Heinz Werner Höppel, Heinz Günter Brokmeier, Werner Skrotzki
Abstract: The plastic anisotropy was studied on aluminium sheets with layers of different purity (A: 5N and B: 2N+) produced by accumulative roll bonding (ARB). Both material layers show a contrasting recrystallization behavior where A and B are discontinuously and continuously recrystallized, respectively. Global textures were measured by neutron diffraction. The mechanical anisotropy was measured by tensile testing after different numbers of ARB cycles. The planar anisotropy decreases with the number of ARB cycles while the normal anisotropy reaches a plateau after 4 cycles. Simulations of the Lankford parameters were carried out with the help of the viscoplastic self-consistent scheme (based on the global texture) and compared with the experimental data. Deviations of the simulated values from those of experiment are discussed with regard to through-thickness texture and material heterogeneities.
Authors: A. Gümbel, L. Ledig, D. Hough, C.G. Oertel, Werner Skrotzki, Jürgen Eckert, Ludwig Schultz
Authors: I. Hünsche, C.G. Oertel, R. Tamm, Werner Skrotzki, W. Knabl
Abstract: Recrystallization is an important tool to adjust the grain size and texture of polycrystalline materials in order to optimize their properties. In the present work recrystallization and the related changes of texture have been studied on rolled molybdenum sheets as a function of temperature and time. The microstructure was investigated by orientation contrast in a scanning electron microscope. The kinetics of recrystallization displayed in a JMAK plot yields Avrami coefficients decreasing with temperature from 2.5 to 1.1. The activation energy amounts to 5 eV, which agrees well with the volume self-diffusion coefficient. The textures of the sheet surface and central layer were measured by X-ray diffraction. The rolling texture in the centre of the sheets is characterized by a strong a-fibre with the rotated cube component {100}<110> dominating. Besides that, there exists a weak g-fibre. In contrast, the surface layer is characterized by a weak cube component. During recrystallization changes in texture are insignificant. With long annealing times all texture components tend to degrade. Conclusions regarding the deep-drawability are drawn.
Authors: Werner Skrotzki, N. Scheerbaum, C.G. Oertel, Heinz Günter Brokmeier, Satyam Suwas, László S. Tóth
Abstract: Aluminum of 5N purity has been deformed at room temperature by equal channel angular pressing using three passes of route A. The microstructure and texture have been investigated by electron back-scattering and neutron diffraction. The microstructure from the first pass on is totally dynamically recrystallized. The recrystallization texture consists of an oblique cube component. The oblate grains and the cube texture are anticlockwise rotated about the transverse direction. The inclination with respect to the extrusion direction depends on the distance from the top of the extruded bar and changes from pass to pass. The mechanism of ormation of the recrystallization microstructure and texture is discussed.
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